I tie 99% of my droppers at the bend of the hook to the fly above it.

The last two years I've been using barbless hooks due to small children in the house.

I don't believe I've lost any more droppers with barbless than I did when I used barbed hooks.

Occaissionally, depending on the line and flies I'm using I'll use the tag end of the surgeons knot as well. For my needs, the bend of the hook usually is a better approach. It's also easier to cast without tangles.

I don't tie droppers to the eye of the previous fly, but I've been known to add a fly with a palomar knot(I may have the name wrong, but it's the knot the drop shot bass fishermen use). I tie flies on small aberdeen hooks for this purpose and they stand straight out from the leader with a weighted fly below them.

Hope this helps,
Jambalaya